In North America, the Emerald Ash Borer has been found in ash trees only. Trees in woodlots as well as landscaped areas are affected. Larval galleries have been in trees or branches measuring as little as 1-inch in diameter. All species of North American ash appear to be susceptible.
The canopy of infested trees begins to thin above the infested portions of the trunk and major branches because the borer destroys the water and nutrient conducting tissues under the bark. Heavily infested trees exhibit canopy die-back usually, starting at the top of the tree. One-third to one-half of the branches may die in one year. Most of the canopy will be dead within 2 years. The adult beetles leave a “D” shaped exit hole in the bark, roughly 1/8 inch in diameter, when they emerge in June. The adult beetle is dark metallic green in color, 1/2 inch long and 1/8 inch wide.
The beetle can have a one or two year life cycle. Adults begin emerging in mid to late May with pre-emergence in late June. Females usually begin laying eggs about 2 weeks after emergence, eggs hatch in 1 – 2 weeks, and the tiny larvae bore through the bark and into the cambium – the area between the bark and wood where nutrient levels are high. The larvae typically pass through four stages eventually reaching a size of roughly 1 to 1.25 inches long. Most Emerald Ash borer larvae over winter in a small chamber in the outer bark or in the outer inch of wood. Pupation occurs in spring and the new generation of adults will emerge in May or early June to begin the cycle again.
Protect your trees with annual applications of Fertilome Soil Insect Drench or spray Fertilome 38 Plus every 10 days from May 20 through June 30. Encourage ash tree growth with annual feedings of Espoma Tree-Tone and irrigate thoroughly June through September.